A rolling bearing is known from the USSR inventor's certificate No. 176468 dated 20 Mar. 1963, international patent classification: F 06C. The above rolling bearing contains inner and outer rings, rolling elements, a cage in the form of a cartridge with teeth on one end. Asymmetric design due to a loose fit of the cartridge bushing on one shaft end is a drawback of the bearing, because in causes cage misalignment. Besides, this design does not provide for the oil supply to the bearing which limits its life time and application area only to low rotation frequencies and low centrifugal overloads.
A bearing is known from the USSR inventor's certificate No. 1328595 dated 13 Jun. 1984, international patent classification: F16 C19/54 which contains a rolling bearing on a shaft and a cogged cage which has an elongated component extending beyond the bearing limits. Additionally a bushing is fastened on the shaft.
It has a collar enveloping the elongated part of the cage. A cavity for bearing lubrication is provided inside the bushing. During operation lubricant from the cavity reaches the bushing, then the cage, bearing and shaft. However, with such a design in addition to spot friction forces between the cage teeth and rolling bodies additional surface friction forces between the outer surfaces of the cage elongated parts and the inner surface of the bushing collar occur. It results in the increase of losses to friction and heat emission associated with it. Losses repeatedly increase due to high centrifugal overloads in planetary mechanisms which causes bearing overheating and jamming. Besides, lubricant quantity is limited by the volume of the lubrication cavity. In order to fill the cavity it is necessary to disassemble the mechanism. It complicates mechanism operation.
The above drawbacks are eliminated in the design of the bearing assembly supported by the patent for an invention No. 2216659 RU of 19 Oct. 2001, international patent classification F16C19/54. The assembly contains a body and a shaft placed inside. A rolling bearing and a cogged cage are installed on the shaft. In addition the assembly is equipped with two coaxial bushings one of which is tightly installed on the shaft and the other one is fastened on the body. The cage is placed in a cylindrical slit between these bushings. The body, shaft and bushings are equipped with interconnected passages for lubricant supply to the cage where there are openings for oil reach. Oil is supplied continuously from an external source.
Such a design reduces friction losses on the cage surface which slides on the oil film between surfaces of the bushing. This allows the cage to withstand practically any loads. Cage location between the additional bushings excludes high-frequency vibrations of the cage caused by bending occurrences and eliminates the fatigue effect on assembly materials. This increases the assembly life time and operating reliability.
However, when a high-speed and high-power load is attached to the shaft, the design of its mounting assembly does not exclude misalignments of bearing rotation axes. It causes their jamming and reduces assembly functional capacity and its application field.
A design with two and more bearings is considered to be the most reliable. In this case the load is connected to the shaft between the bearings and evenly distributed between them. Such arrangement excludes misalignment of bearing rotation shafts and allows increasing the unit life time.
The design of the bearing assembly with two bearings rested on a shaft is given in the FIGURE attached to the above patent No. 2216659. However, to coaxial bushings are located between the bearings, and the cogged cage body is placed between them. It excludes the attachment of a loading gear to the shaft between the bearings.
An example of a mounting assembly with two bearings is given in the RU patent for invention No. 1036981 of 27 May 1982, international patent classification: F16H1/28; 57/08 (prototype). The unit contains a hollow shaft with inner rings of two symmetrical rolling bearings. The rings are fastened on the shaft at intervals. Outer rings of the bearing are installed on the body. Bearing rolling bodies are separated by cages which may be supported either by rolling bodies or by inner or outer rings of the bearings.
However, such designs can work only with low centrifugal speeds and small overloads.
When operating with high speeds cages are exposed to strong centrifugal overloads which are transferred to the components supporting the cages. Contact area of the cage supporting parts with either rolling bodies or rings is very small, thus, even with flood lubrication, it causes strong overheating and wear of both cages and bearing rings, as well as rolling bodies of the bearings. It certainly causes a rapid break down of the assembly and the whole mechanism.